Upright fluid heating furnace with heat recovery system



Jan. 28, 1964 P. KONIEWIEZ ETAL Filed Sept. 28, 1960 5 Sheets-Sheet 1 PAUL KONlEWlEZ GEORGE RUSSELL JAMES VENTORS 1964 P. KONIEWIEZ ETAL 3, 19,671

UPRIGHT FLUID HEATING FURNACE WITH HEAT RECOVERY SYSTEM 5 Sheets-Sheet 2 Filed Sept. 28. 1980 PAUL KONIEWIEZ GEORGE RUSSELL JAMES INVENTORS AGENT Jan. 28, 1964 P. KONIEWIEZ ETAL 3,119,671

UPRIGHT FLUID HEATING FURNACE WITH HEAT RECOVERY SYSTEM 5 Sheets-Sheet 3 Filed Sept. 28, 1960 PAUL KONIEWIEZ GEORGE RUSSELL JAMES INVENTORS BYQ AGENT Jan. 28, 1964 P. KONIEWIEZ ETAL UPRIGHT FLUID HEATING FURNACE WITH HEAT RECOVERY SYSTEM Filed Sept. 28, 1960 5 Sheets-Sheet 4 PAUL KONIEWIEZ GEORGE RUSSELL JAMES INVENTORS AGENT Jan. 28, 1964 P. KONlEWlEZ ETAL 3,119,671

UPRIGHT FLUID HEATING FURNACE WITH HEAT RECOVERY SYSTEM Filed Sept. 28, 1960 5 Sheets-Sheet 5 PAUL KONIEWIEZ GEORGE RUSSELL JAMES INVENTORS BY IZ ML AGENT United States Patent 3,119,671 UPRIGHT FLUID HEATING FURNACE WITH HEAT RECOVERY SYFITEM Paul Koniewiez, Flushing, and George Russell Iames, Armonk, N.Y.; said Paul Koniewiez, now by change of pame Paul Kerwin, and said George Russell James asslgnors to Chemical Construction Corporation, New York, N.Y., a corporation of Delaware Filed Sept. 28, 1960, Ser. No. 58,931 13 Claims. (Cl. 23-277) This invention relates to an improved fluid heating furnace, in particular to an improved hydrocarbon reform furnace. A furnace apparatus with centralized Waste heat recovery elements has been developed, which permits waste heat recovery within the furnace itself. The improved apparatus of the present invention thus provides better recovery of usable heat, while greatly simplifying the overall construction of furnaces for primary hydrocarbon reform or other fluid heating usages.

The present invention will be described in relation to the process of hydrocarbon conversion known as primary reforming, which is widely employed to produce synthesis gas and hydrogen. In this well-known process, a hydrocarbon fluid such as methane is catalytically reacted with steam at elevated temperatures, to produce a reformed gas mixture containing principally hydrogen, carbon mon oxide and carbon dioxide. The overall reaction is endothermic, and consequently the usual practice is to pass the input mixture of hydrocarbon and steam through an externally heated tube or group of tubes. The tubes are packed with solid catalyst granules. The hot product reformed gas mixture is withdrawn from the reformer unit and then passed to further processing. The requisite heating is usually provided by burning a hydrocarbon fuel with air external to the catalyst-filled reformer tubes. Since the reform reaction must be carried out at a highly elevated temperature, the flue gas generated by burning the hydrocarbon fuel is removed at a relatively high temperature. Sensible heat in this flue gas is usually recovered in an auxiliary waste heat boiler.

Thus a typical primary reform installation usually in cludes a reform furnace provided with catalyst-filled reform tubes and burners, together with an induced draft fan, a flue gas waste heat boiler, and disposal stack. In the present invention, a unitary appartus combination is provided whereby all the aforementioned elements are contained in a single apparatus. The advantages of this apparatus arrangement are numerous. More useful heat is recovered, since heat losses are reduced. This is because the apparatus of the present invention is unitary and compact, thus heat losses from transfer ducts, connectors and other external surfaces exposed to ambient temperature conditions are eliminated. In addition, the unitary construction of the apparatus of the present invention is less complex and easier to fabricate than the aggregative designs of the prior art. This in turn results in simpler and cheaper fabrication and erection procedures and costs. Another thermal advantage to the unitary apparatus of the present invention is that, to a limited but significant extent, it becomes possible to recover a portion of the waste heat from the flue gas at a relatively high temperature. This is highly important since, to a certain extent, it results in heat transfer by radiation rather than convection, which is highly advantageous since faster heat transfer and greater efficiency in utilization of heat transfer surface is thereby achieved.

Finally, the unitary arrangement of the apparatus of the present invention now makes it possible to connect individual reformer tubes to major gas transfer ducts by means of standardized linkages, thus eliminating individual design and fabrication of such linkages as found in the prior art. Typical of such prior art is US. Patent No. 2,660,-

3,119,671 Patented Jan. 28, 1964 "ice 0 Ed 519, in which FIGURE 4 clearly demonstrates the individuality and lack of symmetry of such prior art linkages. In the present invention, symmetry of reformer tubes about a central axis is achieved, in a manner so as to permit standardized design and fabrication of these linkages.

It is an object of this invention to provide an improved furnace apparatus for fluid heating, in particular for the primary steam reforming of hydrocarbons.

Another object is to provide an apparatus for the pur pose with unitary centralized arrangement of apparatus elements.

A further object is to provide a single unit of apparatus for this purpose in which the combined reformer and waste heat recovery functions are achieved.

An additional object is to provide an apparatus for this purpose with improved symmetry of elements, with more uniform and equalized heat transfer and improved heat recovery.

Another object is to provide a combined furnace and waste heat boiler apparatus which is of simplified and symmetrical arrangement, thus making possible improved ease of construction and repair.

An object is to provide an improved apparatus for primary hydrocarbon reforming with central waste heat boiler.

Still another object is to provide improved means for radiant heating of reform tubes at the sections of greatest heat consumption.

These and other objects and advantages of the present invention will become evident from the following description of the invention.

Referring to the figures, FIGURE 1 is an elevation view of a preferred embodiment of the present invention. FIGURE 2 is a plan view of the apparatus, taken on section 22 of FIGURE 1. FIGURE 3 is a plan view taken on section 3-3 of FIGURE 1. FIGURE 4 presents an alternative arrangement of reformer tubes and burn ers, and is a plan view similar to FIGURE 3. FIGURE 5 is an isometric view of adjacent reformer tubes, showing tube internals and linkages to transfer manifolds.

Referring now to FIGURE 1, the entire reformer furnace apparatus and waste heat boiler is shown in elevation view. The unit is held in container 1, provided with refractory side lining 2, refractory lined bottom or base 3 and refractory lined top or roof 4. Container 1 is preferably a vertically extending cylinder, although other suitable configurations such as a square or hexagonal cross-section may be adopted and are within the scope and concept of the present invention. In some instances, external refractory linings or insulation, not shown, may also be provided. I

A centrally positioned refractory partition duct 5 is provided within the unit, and extends upwards from base 3 to the proximity of roof 4. A clearance is provided between duct 5 and roof 4, to allow for passage of flue gas downwards into duct 5. Baflies, not shown, may be provided in this clearance space to channel flue gas flow more directly across the upper portions of reformer tubes 6 prior to passage of flue gas into partition duct 5. Boiler water tubes 7 are vertically disposed within partition duct 5, and extend between lower water drum 8 and'upper steam drum 9. Boiler feed water is passed into drum 8 via line 10 and inlet means 11. Steam is withdrawn from drum 9 via valve 12 and line 13. As will be apparent to those skilled in the art, boiler feed water may also be passed into the system via steam drum 9.

The steam boiler units are separately supported by upper and lower support elements independent of the reformer furnace, and thus the boiler extends freely through the reformer unit to allow for differential thermal expansions. The water tubes 7 preferably extend below connections.

base 3, as shown, with flue gas retention header 14 extending between base 3 and manifold 8 to contain the exiting flue gas prior to disposal through flue gas duct 15. Closure between the boiler elements and the furnace section is provided by upper seal means 16 and lower seal means. 17. Various standard steam boiler accessories, such as safety relief valve, blowdown means, auxiliary burner, liquid level controls, pressure gauge, etc., have been omitted from FIGURE 1 in the interest of clarity. It should be understood that such accessories and auxiliaries will be furnished in practice. The water tubes section is preferably provided with flue gas baffles 18, whereby the gas flow path attains a pattern with flow direction components transverse to the boiler tubes 7,

. as shown. This naturally results in improved heat transfer.

Reformer tube assemblies 6 are vertically oriented within the furnace section of the unit. This section is defined by refractory walls 2, base 3, roof 4, and partition 5. Tube assemblies 6 are preferably supported and suspended within the furnace section by upper support means, not shown. Thus tube assemblies 6 hang freely within the furnace section, and expand freely downwards. It should be understood that various known support means for reformer tubes may be employed within the scope of the present invention, such as lower or intermediate supports, fluid transfer connections at the lower ends of the tubes, etc.

Each of tube assemblies 6 consists of a double tube since concentric inner and outer tubes are provided. Broadly speaking, alternative reformer tube configurations may be employed within the scope of the present invention. Thus for example, tube 6 could in some instances consist merely of a single tube packed with catalyst and provided with upper and lower process fluid However, in the preferred embodiment as shown in FIGURE 1, central opening 19 leads to the inner tube, not shown. Outer opening 20 leads to the annular space between an inner and outer tube. Manifold 21 is connected by identical and interchangeable linkages 22 with openings 19, While manifold 23 is connected by another group of similarly identical linkages 39 with openings 20. It should be understood that all of linkages 22 are identical with each other, however, linkages 22 are of necessity geometrically dissimilar to the linkages 39 which connect manifold 23 with openings 20.' The preferred mode of operation, with the annular space between the inner and outer tubes filled with catalyst, is to pass the inlet mixture of fluid hydrocarbonand steam via duct 24 through manifold 23 and linkages 39 into openings 20, with product reformed gas removal via openings 19, linkages 22 and manifold 21 to duct 25. However, it will be readily appreciated that the flow sequence may be reversed, thus manifold 21 may receive the inlet mixture of steam and fluid hydrocarbon from circular distribution duct 25, with manifold 23 serving to collect and transfer the outlet reformed gas mixture to circular duct 24.

The reformer tube assemblies 6 are externally heated by fluid hydrocarbon burners 26, positioned in base 3. Other burners, not shown, may also be positioned along wall 2 to assist in providing uniform temperature conditions within the furnace. Burner 26 burns a suitable fluid hydrocarbon fuel with air to generate and maintain a highly elevated temperature in the furnace section.

1 The temperature is usually maintained above 1700" F.

in this section of the unit, so as to provide predominantly radiant heating of reformer tube assemblies 6. The rising hot flue gas also heats metallic plates 27 which are suspended at the top of the furnace section between banks of tubes. Plates 27 provide a further radiating heat effect in the upper portion of the unit, where heat consumption is greatest.

In operation, the catalyst packed reformer tubes are externally heated in the furnace section, primarily by radiant heat. The hydrocarbon-steam mixture is passed into the catalyst-packed annular section of each reformer tube via manifold 23 and linkages 39 to openings 20. The gas mixture is heated and catalytically reformed while passing downwards through this annular section. The reformed gas mixture is centrally passed upwards through the inner tube, and is withdrawn from the reformer tube assembly 6 via outlet 19, linkage 22 and manifold 21.

The rising hot flue gas from burners 26, after serving to heat reformer tube assemblies 6 and plates 27, passes centrally inwards through the clearance or openings between partition duct 5 and roof 4. The flue gas then passes downwards within partition duct 5 to retention header 14, and heats boiler feed water inside water tubes 7, thus generating steam. The steam rises inside tubes 7 and is collected in drum 9, and withdrawn via valve 12 and line 13. Makeup boiler feed water is passed into drum 3 via line 10 and feed inlet means 11.

The cooled flue gas now passes via duct 15 to external disposal. The flue gas will usually still contain sufficient low-level sensible heat to warrant provision of a further heat recovery unit such as gas-to-gas heat exchanger 28. Thus, in a preferred embodiment, heat exchanger 28 is combined with the balance of the apparatus so as to preheat the combustion air passed to burners 26. The input air stream 29 is directed through inlet duct 30 by blower 31, and is heated in the tube side of exchanger 28. The hot air now passes via duct 32 to lower air manifold 33 below base 3. Manifold 33 serves to deliver the preheated hot air to burners 26. It should .be understood that exchangers similar to heat exchanger 28 may also be alternatively or additionally employed to preheat the fluid hydrocarbon fuel being passed to burners 26 via 34 or to preheat the boiler feed water being passed via 10 to drum 8 or for other heating purposes.

The flue gas is finally dispersed to atmosphere via duct 43 and stack 35. Induced draft fan 36 may be provided inside stack 35 to assist in providing sufficient overall furnace draft.

It will readily be appreciated that, in practice, one of the main features and advantages of the apparatus of the present invention is the relative ease of repair or replacement of units or elements which is made possible by the unique apparatus configuration. Thus, because of the suspension of the waste heat boiler inside the furnace section, high temperature seals and connection ducts are eliminated. In addition, differential thermal expansion and alignment problems are also avoided. In practice, the waste heat boiler opening in roof 4, defined by seal 16, is slightly larger than the lower opening in base 3 defined by seal 17. This configuration greatly facilitates the removal of the entire waste heat boiler section for repair or overhaul, since it thus may readily be lifted upwards and out of the unit on such occasions. The waste heat boiler unit may optionally be supported by support means attached to roof 4 or support means 41 attached to upper beams 42. In this case, the entire unit would hang freely from the alternative upper suspension, and sealing means 16 would be replaced by a support element which would also serve as a seal.

Referring now to FIGURE '2, which is a plan view of the apparatus taken on section 2-2, the symmetry and uniformity of the piping linkages to the individual reformer tubes is readily apparent. The input gas mixture of steam and fluid hydrocarbon is passed into reformer tubes 6 via duct 24, manifolds 23 and linkages 39. The reformed gas mixture is derived from individual reformer tubes 6 through each of central opening 19, and passes through each of linkages 22 to manifolds 21. Circular product removal duct 25 not visible in the this view receives product reformed gas mixture from each of manifolds 21, and thereafter transfer the gas mixture out of the unit by conduit means, not shown. It should be noted that this apparatus arrangement achieves standardized and uniform dimensioning of linkages 22, whereas the di mensions of prior art linkages had to be individually designed for each reformer tube due to the basic arrangement of the apparatus, as for example in US. Patent No. 2,660,519. The linkages 39 between manifolds 23 and outer openings 20 in the reformer tubes have also been indicated. Openings 20 are not visible in this view. Manifolds 23 will obviously be disposed above manifolds 21, as shown in FIGURE 1. In addition, each manifold 23 is displaced to the opposite side of each bank of tubes from the corresponding manifold 21.

FIGURE 3 is a sectional plan view of the apparatus, taken on section 3-3 of FIGURE 1. FIGURE 3 shows the preferred arrangement of reformer tubes 6 within the furnace section, namely in linear banks of tubes radiating from the geometric center of the unit. Burners 26 are correspondingly arranged symmetrically in groups within each section, between successive banks of tubes. It will be understood that, in practice, the linear spacing between adjacent reformer tubes 6 in each bank may be varied, as well as the linear spacing between adjacent burners 26 in each group of burners. Thus, although the apparatus is shown with identical spacing between tubes and also between burners, in practice it will prove advantageous in some instances to vary these spacings, pasticularly by providing more spacing between burners nearer the center of the apparatus. The reason for this is because, in practice, a temperature gradient may be established in the furnace section, with higher temperatures towards the center of the apparatus, due to geometric concentration of burners. Thus, providing greater spacing between burners, or less spacing between reformer tubes which are disposed nearer to the center of the apparatus serves to provide more uniform temperature within the furnace section.

FIGURE 3 further shows a cross-sectional view of the internal arrangement of reformer tubes 6. Thus catalyst bed 37 is shown disposed in the annular space between tube 6 and central reformed gas return tube 38. FIGURE 3 also shows, in cross-section, partition duct and steam boiler tubes 7.

FIGURE 4 is typical of one of the numerous alternative arrangements of reformer tubes and burners which may be adopted in the apparatus of the present invention. In FIGURE 4, burners 26 and reformer tubes 6 are shown arranged in alternate concentric circular groupings within the furnace section. Such an arrangement would prove advantageous in larger installations, however, in generfl the linear radial banks grouping previously described are preferred, due to the symmetry and uniformity of manifolding and linkages which is thereby achieved.

FIGURE 5 presents an isometric view of adjacent reformer tubes in a bank, showing linkages to transfer manifolds in perspective. In addition, tube internals are also illustrated in cutaway view for additional clarification of the reformer tube internals. Thus the incoming feed gas mixture of hydrocarbon and steam passes into the apparatus via circular duct 24 from an external supply source, not shown. The feed stream flows from duct 24 to manifold 23, through linkages 39 to openings 20, and finally to individual reformer tubes 6. The feed mixture is now heated and catalytically converted to reformed gas, while passing downwards through the annular space between reformer tube 6 and inner return tube 38. The gas is, of course, in contact with catalyst bed 37 while thus passing downwards. Bed 37 is retained by screen support means 40, so that the reformed gas stream freely passes into the inner return tube 38 at the bottom of tube 6.

The reformed gas stream now passes upwards through central return tube 38, and out of the reformer tube to manifold 21 through upper outlet 19 and linkage 22. From manifold 21 the reformed gas proceeds to circular duct 25 and thence out of the apparatus.

Typical operating conditions for the apparatus of the 6 present invention include a furnace section operating terriper-ature between 1700 F. to 2000 F., with initial flue gas temperature of about 1700 F. before passage through the waste heat boiler section of the apparatus. Final flue gas temperature is about 500 F. Boiler feed water input temperature is 220 F., with outlet steam temperature of 420 -F. (300 p.s.i.g. steam). Net steam production is 14,000 pounds per hour plus 1500 pounds per hour blowdown, for a flue gas flow rate of 1750 mols per hour.

It should be understood that various modifications and equivalents are within the scope of the present invention. Thus for example, the waste heat boiler apparatus could be utilized with modifications as a conventional heat exchanger if so desired. In such instances the inlet drum 8 would be supplied with a conventional high temperature heat exchange fluid such as Dowtherm, with removal of heated fluid from upper drum 9 to external utilization as a heat source and subsequent recycle to inlet drum 8.

The broadest scope of utilization of the apparatus of the present invention is as a generalized fluid heating furnace. In this case reformer tubes 6 would be supplied with fluid to be heated or thermally converted or treated, either catalytically or otherwise. In this respect various alternative or equivalent linkage arrangements for the reformer tubes, similar to those duct and linkages illustrated, will occur to those skilled in the art. For example, it will be understood that one suitable modification for generalized fluid heating would be to extend reformer tubes 6 through base 3 and provide lower external connections to the tubes whereby the fluid to be heated is simply passed only once through the tubes, either from top to bottom or vice versa. Alternative or auxiliary bot tom supports may also be provided for the tubes 6. Likewise, intermediate supports may be provided. Other variations and modifications Within the scope of the present invention will occur to those skilled in the art.

We claim:

1. Upright fluid heating furnace with integral heat recovery unit comprising a vertically extending cylindrical refractory-lined container, a concentric circular partition duct coaxially aligned within said container and extending upwards from the :base of said container, said partition duct terminating near the top of said container, a plurality of vertically oriented heater tubes disposed within said container in the annular furnace section external to said partition duct, means for passing process fluid through said heater tubes, a plurality of hydrocarbon combustion burners positioned in the base of said container and external to said partition duct, means for conducting fluid hydrocarbon fuel and air to said burners, a plurality of vertically oriented boiler water tubes disposed within said partition duct and extending below the base of said container, means for passing boiler feed water into said boiler tubes, steam recovery means connected to the upper ends of said boiler tubes, a flue gas retention header at the base of said container, said header extending between said partition duct and said boiler feed water inlet means, and flue gas disposal means connected to an outlet in said retention header, whereby flue gas from said burners is first directed upwards through said annular furnace section, then downwards within said partition duct to said retention header, and finally through said header outlet to said disposal means.

2. Apparatus of claim 1, in which said heater tubes are arranged in a plurality of linear banks, said banks of tubes being positioned symmetrically about the axis of said container, with each of said banks extending radially to said axis in the annular furnace section between said partition duct and said container.

3. Apparatus of claim 2, in which said burners are arranged in a plurality of linear groups, with each group of burners positioned and extending symmetrically equidistant from an adjacent pair of tube banks, and with each group of burners extending radially relative to said container axis, at the bottom of said annular furnace section.

4. Hydrocarbon reformer furnace comprising a -vertically extending container, a vertical partition duct centrally disposed said container, said partition duct extending upwards from the base of said container and terminating near the top of said container, a plurality of vertically oriented catalyst-laden reformer tubes disposed within said container and external to said partition duct, means for passing a mixture of fluid hydrocarbon and steam into said reformer tubes, means for recovering reformed gas mixture from said reformer tubes, a plurality of hydrocarbon combustion burners positioned in the base of said container and external to said partition duct, means for conducting fluid hydrocarbon fuel and oxygencontaining gas to said burners, a plurality of vertically oriented heat recovery tubes disposed within said partition duct, means for passing heat exchange fluid into said heat recovery tubes, means for recovering heat exchange fluid with higher heat content from said heat recovery tubes, and flue gas disposal means connected to a flue gas outlet near the lower end of said partition duct, whereby flue gas from said burners is first directed upwards past said heater tubes, then downwards within said partition duct, and finally through said flue gas outlet to disposal means.

5. Apparatus of claim 4, in which said heat recovery tubes comprise boiler water tubes, said means for passing heat exchange fluid into said heat recovery tubes comprise means for passing boiler feed water into said tubes, and said means for recovering heat exchange fluid with higher heat content from said heat recovery tubes comprise steam recovery means connected to the upper ends of said tubes.

6. Apparatus of claim 4, in which said flue gas disposal means comprises an external heat exchanger for additional recovery of heat from said flue gas, together with means for passing heat exchange fluid through said heat exchanger, and a flue gas stack extending upwards from said external heat exchanger for final flue gas disposal.

7. Apparatus of claim 6, in which said means for passing heat exchange fluid through said heat exchanger comprises an inlet duct for conducting into said heat exchanger and an outlet duct for conducting heated air from said heat exchanger to said hydrocarbon combustion burners. I

8. Hydrocarbon reformer furnace comprising a vertically extending cylindrical refractory-lined container, a concentric circular partition duct coaxially aligned within said container and extending upwards from the base of said container, said partition duct terminating near the top of said container, a plurality of catalyst-laden reformer tubes vertically suspended in the annular furnace section within said container and external to said partition duct by means of upper supports attached to the top of said container, means for admitting a mixture of fluid hydrocarbon and steam into said reformer tubes, means for removing reformed gas mixturefrom s-aid reformer tubes, a plurality of hydrocarbon combustion burners positioned in the base of said container and external to said partition duct, means for conducting fluid hydrocarbon fuel and air to said burners, a plurality of'vert'ically oriented boiler water tubes disposed within said partition duct and extending below the base of said container, means for passing boiler feed water into said boiler tubes, steam recovery means connected to the upper ends of said boiler tubes, a flue gas retention header at the base of said container, said header extending downwards from said partition duct and enclosing the portion of said boiler tubes below the base of said container, and flue gas disposal means connected to an outlet in said retention header, whereby flue gas from said burners is first directed upwards through said annular furnace section, then downwards within said partition duct to said retention header, and finally through said header outlet to said disposal means.

9. Apparatus of claim 8, in which each of said reformer tubes comprises an inner tube and a concentric outer tube, with the annular space between said inner and outer tubes being filled with catalyst, said inner tube being open at its lower end, said outer tube extending below said inner tube and being closed at its lower end, and said means for admitting hydrocarbon-steam mixture to and removing reformed gas mixture from each ofsaid reformer tubes being connected to the upper end of each reformer tube.

10. Apparatus of claim 9, in which said means for admitting hydrocarbon-steam mixture to said reformer tubes is connected to said concentric outer tube, whereby said means directs said hydrocarbon-steam mixture into the upper section of the annular space between said inner and outer tubes, and said means for removing reformed gas mixture from said reformer tubes is connected to said inner tube.

11. Apparatus of claim 8, in which said reformer tubes are arranged in a plurality of linear banks, said banks of tubes being positioned symmetrically about the axis of said container, with each of 'said banks extending radially to said axis in the annular furnace section between said partition duct and said container.

12. Apparatus of claim 11, in which said burners are arranged in a plurality of linear groups, with each group of burners positioned symmetrically equidistant between an adjacent pair of tube banks, and with each group of burners extending radially relative to said container axis.

13. Apparatus of claim 11, in which a radiant heating plate is suspended between adjacent tube banks in the upper portion of said furnace, whereby the upper sections of said tubes are at least partially heated by radiant heat emanating from said plate.

References Cited in the file of this patent UNITED STATES PATENTS 1,894,215 Brandt Jan. 10, 1933 2,173,844 Houdry Sept. 26, :1939 2,184,465 3 Ocon Dec. 26, 1939 2,660,519 McCarthy Nov. 24, 1953 2,688,589 Campbell et a1. Sept. 7, 1954 

1. UPRIGHT FLUID HEATING FURNACE WITH INTEGRAL HEAT RECOVERY UNIT COMPRISING A VERTICALLY EXTENDING CYLINDRICAL REFRACTORY-LINED CONTAINER, A CONCENTRIC CIRCULAR PARTITION DUCT COAXIALLY ALIGNED WITHIN SAID CONTAINER AND EXTENDING UPWARDS FROM THE BASE OF SAID CONTAINER, SAID PARTITION DUCT TERMINATING NEAR THE TOP OF SAID CONTAINER, A PLURALITY OF VERTICALLY ORIENTED HEATER TUBES DISPOSED WITHIN SAID CONTAINER IN THE ANNULAR FURNACE SECTION EXTERNAL TO SAID PARTITION DUCT, MEANS FOR PASSING PROCESS FLUID THROUGH SAID HEATER TUBES, A PLURALITY OF HYDROCARBON COMBUSTION BURNERS POSITIONED IN THE BASE OF SAID CONTAINER AND EXTERNAL TO SAID PARTITION DUCT, MEANS FOR CONDUCTING FLUID HYDROCARBON FUEL AND AIR TO SAID BURNERS, A PLURALITY OF VERTICALLY ORIENTED BOILER WATER TUBES DISPOSED WITHIN SAID PARTITION DUCT AND EXTENDING BELOW THE BASE OF SAID CONTAINER, MEANS FOR PASSING BOILER FEED WATER INTO SAID BOILER TUBES, STEAM RECOVERY MEANS CONNECTED TO THE UPPER ENDS OF SAID BOILER TUBES, A FLUE GAS RETENTION HEADER AT THE BASE OF SAID CONTAINER, SAID HEADER EXTENDING BETWEEN SAID PARTITION DUCT AND SAID BOILER FEED WATER INLET MEANS, AND FLUE GAS DISPOSAL MEANS CONNECTED TO AN OUTLET IN SAID RETENTION HEADER, WHEREBY FLUE GAS FROM SAID BURNERS IS FIRST DIRECTED UPWARDS THROUGH SAID ANNULAR FURNACE SECTION, THEN DOWNWARDS WITHIN SAID PARTITION DUCT TO SAID RETENTION HEADER, AND FINALLY THROUGH SAID HEADER OUTLET TO SAID DISPOSAL MEANS. 